Heat transfer method

ABSTRACT

The present invention relates to a method of heat transfer by means of a composition containing hydrochlorofluoroolefins. The subject matter of the present invention is more particularly a heat transfer method comprising, successively, a step of evaporation of a coolant fluid, a compression step, a step of condensation of said fluid at a temperature of greater than or equal to 70° C. and a step of expansion of said fluid, characterized in that that coolant fluid comprises at least one hydrochlorofluoroolefin.

The present invention relates to a heat transfer process using acomposition containing hydrochlorofluoroolefins. It relates moreparticularly to the use of a composition containinghydrochlorofluoroolefins in heat pumps.

The problems posed by substances which deplete the atmospheric ozonelayer (ODP: ozone depletion potential) were tackled at Montreal, wherethe protocol imposing a reduction in the production and use ofchlorofluorocarbons (CFCs) was signed. This protocol has been thesubject of amendments which have required that CFCs be withdrawn andhave extended regulatory control to other products.

The refrigeration industry and the air conditioning industry haveinvested a great deal in the replacement of these refrigerant fluids.

In the automotive industry, the air conditioning systems for vehiclessold in many countries have changed from a chlorofluorocarbon (CFC-12)refrigerant fluid to a hydrofluorocarbon (1,1,1,2-tetrafluoroethane:HFC-134a) refrigerant fluid which is less harmful to the ozone layer.However, from the viewpoint of the objectives set by the Kyoto protocol,HFC-134a (GWP=1300) is regarded as having a high warming potential. Thecontribution to the greenhouse effect of a fluid is quantified by acriterion, the GWP (Global Warming Potential), which indexes the warmingpotential by taking a reference value of 1 for carbon dioxide.

As carbon dioxide is non-toxic and non-flammable and has a very low GWP,it has been proposed as a refrigerant fluid for air conditioning systemsas a replacement for HFC-134a. However, there are several disadvantagesto the use of carbon dioxide, related in particular to the very highpressure of the use thereof as a refrigerant fluid in existing devicesand technologies.

Document JP 4110388 describes the use of hydro-fluoropropenes of formulaC₃H_(m)F_(n) with m and n representing an integer between 1 and 5inclusive and m+n=6, as heat transfer fluids, in particulartetrafluoropropene and trifluoropropene.

Document WO 2004/037913 discloses the use of compositions comprising atleast one fluoroalkene having three or four carbon atoms, in particularpentafluoropropene and tetrafluoropropene, preferably having a GWP atmost of 150, as heat transfer fluids.

In document WO 2007/002625, fluorohaloalkenes having from to 6 carbonatoms, in particular tetrafluoropropenes, pentafluoropropenes andchlorotrifluoropropenes, have been described as capable of being used asa heat transfer fluid.

In the field of heat pumps, substitutes for dichlorotetrafluoroethane(HCFC-114), used under conditions of high condensing temperature, havebeen proposed. Thus, document U.S. Pat. No. 6,814,884 describes acomposition comprising 1,1,1,3,3-pentafluorobutane (HFC-365mfc) and atleast one compound chosen from 1,1,1,2-tetrafluoroethane,pentafluoroethane (HFC-125), 1,1,1,3,3-pentafluoropropane (HFC-245fa)and 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea). However, thesecompounds have a high GWP.

The applicant has now discovered that compositions containinghydrochlorofluoroolefins are very particularly suitable as heat transferfluid in heat pumps, in particular heat pumps that operate at a highcondensing temperature. Moreover, these compositions have a negligibleODP and a GWP below that of existing heat transfer fluids.

The term “hydrochlorofluoroolefins” is understood to mean olefins havingfrom 3 to 4 carbon atoms that comprise one chlorine atom and at leastone fluorine atom. Preferably, the chlorine atom is borne by theunsaturated carbon.

A heat pump is a thermodynamic device allowing the transfer of heat fromthe coldest medium to the hottest medium. The heat pumps used forheating are referred to as compression heat pumps and the operation isbased on the principle of the compression cycle of fluids, referred toas refrigerant fluids. These heat pumps operate with compression systemscomprising a single or several stage(s). At a given stage, when therefrigerant fluid is compressed and passes from the gaseous state to theliquid state, an exothermic reaction (condensation) takes place thatproduces heat. Conversely, if the fluid is expanded by passing it fromthe liquid state to the gaseous state, an endothermic reaction(evaporation) takes place, which produces a cold sensation. Everythingtherefore relies on the change of state of a fluid used in a closedcircuit.

Each stage of a compression system comprises (i) a step of evaporationduring which, in contact with heat drawn from the surroundings, therefrigerant fluid, by virtue of its low boiling point, changes from theliquid state to the gaseous state, (ii) a step of compression duringwhich the gas from the preceding step is brought to high pressure, (iii)a step of condensation during which the gas will transmit its heat tothe heating circuit; the refrigerant, still compressed, becomes liquidagain and (iv) a step of expansion during which the pressure of thefluid is reduced. The fluid is ready for a new absorption of heat fromthe cold environment.

One subject of the present invention is a heat transfer process using acompression system having at least one stage successively comprising astep of evaporation of a refrigerant fluid, a step of compression, astep of condensation of said fluid at a temperature greater than orequal to 70° C. and a step of expansion of said fluid characterized inthat the refrigerant fluid comprises at least onehydrochlorofluoroolefin.

Preferably, the condensing temperature of the refrigerant fluid isbetween 70 and 140° C., and advantageously between 95 and 125° C.

Preferably, the hydrochlorofluoroolefins comprise at least threefluorine atoms.

Particularly advantageous hydrochlorofluoroolefins arechlorotrifluoropropenes (HCFO-1233), in particular1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) and2-chloro-3,3,3-trifluoropropene (HCFO-1233xf). The1-chloro-3,3,3-trifluoropropene may be in either cis form or trans form.

Besides the hydrochlorofluoroolefin(s), the refrigerant fluid maycomprise at least one hydrofluorocarbon.

As hydrofluorocarbons, mention may especially be made of1,1,1,3,3-pentafluorobutane, 1,1,1,2-tetrafluoroethane,pentafluoroethane, 1,1,1,3,3-pentafluoropropane,1,1,1,2,3-pentafluoropropane, 1,1,1,2,2-penta-fluoropropane and1,1,1,2,3,3,3-heptafluoropropane.

The refrigerant fluid may also comprise at least one fluoroether,preferably at least one hydrofluoroether and advantageously at least onehydrofluoroether having from three to six carbon atoms.

As hydrofluoroethers, mention may especially be made ofheptafluoromethoxypropane, nonafluoromethoxybutane andnonafluoroethoxybutane. The hydrofluoroether is available in severalisomeric forms such as 1,1,1,2,2,3,3,4,4-nonafluoroethoxybutane,1,1,1,2,3,3-hexafluoro-2-(trifluoromethyl)-3-ethoxybutane,1,1,1,2,2,3,3,4,4-nonafluoromethoxybutane and1,1,1,2,3,3-hexafluoro-2-(trifluoromethyl)-3-methoxybutane.

The refrigerant fluid may also comprise at least one fluoroalkene havingfrom 3 to 6 carbon atoms. Preferably, the fluoroalkene is chosen fromfluoropropenes, in particular trifluoropropenes such as1,1,1-trifluoropropene, tetrafluoropropenes such as2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,3,3,3-tetrafluoropropene andfluorobutenes. Fluoromethyl-propenes may be suitable.

Preferably, the refrigerant fluid comprises at least 10% by weight ofhydrochlorofluoroolefins.

The refrigerant fluid used in the present invention may comprise astabilizer of the hydrochlorofluoroolefin. The stabilizer represents atmost 5% by weight relative to the total composition of the fluid.

As stabilizers, mention may especially be made of nitromethane, ascorbicacid, terephthalic acid, azoles such as tolutriazole or benzotriazole,phenolic compounds such as tocopherol, hydroquinone,t-butylhydroguinone, 2,6-di-cert-butyl-4-methylphenol, epoxides (alkyl,optionally fluorinated or perfluorinated, or alkenyl or aromaticepoxides) such as n-butyl glycidyl ether, hexanediol diglycidyl ether,allyl glycidyl ether or butylphenyl glycidyl ether, phosphites,phosphates, phosphonates, thiols and lactones.

The refrigerant used in the process according to the present inventionmay comprise lubricants such as mineral oil, alkylbenzene, polyalkyleneglycol and polyvinyl ether.

EXPERIMENTAL SECTION

In what follows:

Evap P is the pressure at the evaporator

Cond P is the pressure at the condenser

T cond is the condensing temperature

Te comp is the compressor inlet temperature

Ratio: the compression ratio

T outlet comp is the compressor outlet temperature

COP: coefficient of performance and is defined, where a heat pump isconcerned, as being the useful heat power provided the system over thepower taken in or consumed by the system

CAP: volumetric capacity, heat capacity per unit volume (kJ/m³)

% CAP or COP is the ratio of the value of the CAP or COP of the fluidrelative to that obtained with HCFC-114.

EXAMPLE 1

The performances of the refrigerant fluid under the heat pump operatingconditions and by setting the temperature at the evaporator to 10° C.and that at the condenser to 100° C. are given below.

For HCFC-114, the nominal operating pressure is 14.19 bar, thevolumetric capacity is 785 kJ/m³ and the COP is 2.07 under the followingoperating conditions:

Isentropic efficiency of the compressor: 80%

HFC-365mfc/ HCFC-114 HFC-365mfc HCFO-1233zd HFC-227ea Temp evap 10 10 1010 (° C.) T e comp 15 15 15 15 Evap P (kPa) 129 30 76 Cond P (kPa) 1419590 1048 Ratio (p/p) 11.04 19.81 13.72 27.1 T cond (° C.) 100 100 100100 T outlet 100 100 103 comp (° C.) CAP (kJ/m³) 785 260 630 374 COP2.07 2.30 2.42 2.40 % CAP 100 33 80 48 % COP 100 111 117 116

EXAMPLE 2

The performances of the refrigerant fluid under the heat pump operatingconditions and by setting the temperature at the evaporator to 50° C.and that at the condenser to 80° C. are given below.

For HCFC-114, the nominal operating pressure is 9.3 bar, the volumetriccapacity is 3321 kJ/m³ and the COP is 8.19 under the following operatingconditions:

Isentropic efficiency of the compressor: 80%

HCFC-114 HFC-365mfc HCFO-1233zd Temp outlet evap (° C.) 50 50 50 T ecomp (° C.) 65 65 65 Evap P (kPa) 447 142 298 Cond P (kPa) 930 352 663Ratio(p/p) 2.08 2.48 2.22 T cond (° C.) 80 80 80 T outlet comp (° C.) 9087 94 CAP (kJ/m³) 3321 1394 2554 COP 8.19 8.60 8.53 % CAP 100 42 77 %COP 100 105 104

EXAMPLE 3

The performances of the refrigerant fluid under the heat pump operatingconditions and by setting the temperature at the evaporator to 50° C.and the temperature at the condenser to 95° C. are given below.

For HCFC-114, the nominal operating pressure is 12.82 bar, thevolumetric capacity is 2976 kJ/m³ and the COP is 5.19 under thefollowing operating conditions:

Isentropic efficiency of the compressor: 80%

HCFC- HFC- HCFO- HFO- 114 365mfc 1233zd 1234yf Temp evap (° C.) 50 50 5050 T e comp (° C.) 65 65 65 65 Evap P (kPa) 447 142 298 1283 Cond P(kPa) 1282 522 939 3345 Ratio (p/p) 2.87 3.67 3.15 2.61 T cond (° C) 9595 95 95 T outlet comp (° C.) 103 98 107 113 CAP (kJ/m³) 2976 1284 23794065 COP 5.19 5.56 5.56 2.80 % CAP 100 43 80 137 % COP 100 107 107 54

EXAMPLE 4

The performances of the refrigerant fluid under the heat pump operatingconditions and by setting the temperature at the evaporator to 50° C.and that at the condenser to 110° C. are given below.

For HCFC-114, the nominal operating pressure is 17.26 bar, thevolumetric capacity is 2573 kJ/m³ and the COP is 3.56 under thefollowing operating conditions:

Isentropic efficiency of the compressor: 80%

HCFC-114 HFC-365mfc HCFO-1233zd Temp evap (° C.) 50 50 50 T e comp (°C.) 65 65 65 Evap P (kPa) 447 142 298 Cond P (kPa) 1726 748 1294 Ratio(p/p) 3.86 5.26 4.34 T cond (° C.) 110 110 110 T outlet comp (° C.) 116110 121 CAP (kJ/m³) 2573 1157 2172 COP 3.56 3.97 4.00 % CAP 100 45 84 %COP 100 111 112

EXAMPLE 5

The performances of the refrigerant fluid under the heat pump operatingconditions and by setting the temperature at the evaporator to 50° C.and that at the condenser to 120° C. are given below.

For HCFC-114, the nominal operating pressure is 20.82 bar, thevolumetric capacity is 2257 kJ/m³ and the COP is 2.79 under thefollowing operating conditions:

Isentropic efficiency of the compressor: 80%

HCFC-114 HFC-365mfc HCFO-1233zd Temp evap (° C.) 50 50 50 T e comp 65 6565 Evap P (kPa) 447 142 298 Cond P (kPa) 2082 936 1581 Ratio (p/p) 4.666.58 5.30 T cond (° C.) 120 120 120 T outlet comp (° C.) 125 120 130 CAP(kJ/m³) 2257 1063 2015 COP 2.79 3.25 3.29 % CAP 100 47 89 % COP 100 116118

EXAMPLE 6

The performances of the refrigerant fluid under the heat pump operatingconditions and by setting the temperature at the evaporator to 80° C.and that at the condenser to 110° C. are given below.

For HCFC-114, the nominal operating pressure is 17.26 bar, thevolumetric capacity is 5475 kJ/m³ and the COP is 7.94 under thefollowing operating conditions:

Isentropic efficiency of the compressor: 80%

HCFC-114 HFC-365mfc HCFO-1233zd Temp evap (° C.) 80 80 80 T e comp (°C.) 90 90 90 Evap P (kPa) 930 352 663 Cond P (kPa) 1726 748 1294 Ratio(p/p) 1.86 2.12 1.95 T cond (° C.) 110 110 110 T outlet comp (° C.) 116111 117 CAP (kJ/m³) 5475 2872 4705 COP 7.94 8.83 8.72 % CAP 100 52 86 %COP 100 111 110

EXAMPLE 7

The performances of the refrigerant fluid under the heat pump operatingconditions and by setting the temperature at the evaporator to 80° C.and that at the condenser to 120° C. are given below.

For HCFC-114, the nominal operating pressure is 20.82 bar, thevolumetric capacity is 4810 kJ/m³ and the COP is 5.45 under thefollowing operating conditions:

Isentropic efficiency of the compressor: 80%

HCFC-114 HFC-365mfc HCFO-1233zd Temp evap (° C.) 80 80 80 T e comp (°C.) 90 90 90 Evap P (kPa) 930 352 663 Cond P (kPa) 2082 936 1581 Ratio(p/p) 2.24 2.66 2.38 T cond (° C.) 120 120 120 T outlet comp (° C.) 126120 127 CAP (kJ/m³) 4810 2648 4360 COP 5.45 6.36 6.24 % CAP 100 55 91 %COP 100 117 114

EXAMPLE 8

The performances of the refrigerant fluid under the heat pump operatingconditions and by setting the temperature at the evaporator to 80° C.and that at the condenser to 130° C. are given below.

For HCFC-114, the nominal operating pressure is 24.92 bar, thevolumetric capacity is 4027 kJ/m³ and the COP is 3.79 under thefollowing operating conditions:

Isentropic efficiency of the compressor: 80%

HCFC-114 HFC-365mfc HCFO-1233zd Temp evap (° C.) 80 80 80 T e comp (°C.) 90 90 90 Evap P (kPa) 930 352 663 Cond P (kPa) 2492 1157 1913 Ratio(p/p) 2.68 3.28 2.88 T cond (° C.) 130 130 130 T outlet comp (° C.) 136130 136 CAP (kJ/m³) 4027 2403 3967 COP 3.79 4.81 4.71 % CAP 100 60 99 %COP 100 127 124

EXAMPLE 9

The performances of the refrigerant fluid under the heat pump operatingconditions and by setting the temperature at the evaporator to 80° C.and that at the condenser to 140° C. are given below.

For HCFC-114, the nominal operating pressure is 29.61 bar, thevolumetric capacity is 2971 kJ/m³ and the COP is 2.46 under thefollowing operating conditions:

Isentropic efficiency of the compressor: 80%

HCFC-114 HFC-365mfc HCFO-1233zd Temp evap (° C.) 80 80 80 T e comp (°C.) 90 90 90 Evap P (kPa) 930 352 663 Cond P (kPa) 2961 1417 2295 Ratio(p/p) 3.19 4.02 3.46 T cond (° C.) 140 140 140 T outlet comp (° C.) 147140 147 CAP (kJ/m³) 2971 2134 3520 COP 2.46 3.73 3.62 % CAP 100 72 118 %COP 100 152 147

1. A heat transfer process using a compression system comprisingsuccessively a step of evaporation of a refrigerant fluid, a step ofcompression of said refrigerant fluid, a step of condensation of saidrefrigerant fluid at a temperature greater than or equal to 70° C. and astep of expansion of said refrigerant fluid characterized in that therefrigerant fluid comprises at least one hydrochlorofluoroolefin.
 2. Theprocess as claimed in claim 1, characterized in that the temperature isbetween 70 and 140° C.
 3. The process as claimed in claim 1,characterized in that the refrigerant fluid comprises at least onehydrofluorocarbon.
 4. The process as claimed in claim 1, characterizedin that the refrigerant fluid comprises at least one hydrofluoroether.5. The process as claimed in claim 1, characterized in that therefrigerant fluid comprises at least one fluoroalkene.
 6. The process asclaimed in claim 1, characterized in that the hydrochlorofluoroolefincomprises at least three fluorine atoms.
 7. The process as claimed inclaim 1, characterized in that the hydrochlorofluoroolefin is selectedfrom the group consisting of 1-chloro-3,3,3-trifluoropropene and2-chloro-3,3,3 -trifluoropropene.
 8. The process as claimed in claim 1,characterized in that the temperature is between 95 and 125° C.